JP2023504700A - Device for driver-specific backout prevention - Google Patents

Abstract

A driver-specific anti-backout mechanism is disclosed that includes a screw and a body. A first driver may be used to connect and disconnect the screw to and from the body, while a second driver may be used only to adjust the position of the screw within the receiving body. The body includes a cavity for receiving the head of the screw, the cavity having an inwardly directed flange. The screw includes an upper socket and a lower socket, a channel extends from the lower socket through the head, and the lock body is disposed within the channel. Engagement with the first driver allows the lock body to move so that fasteners can be inserted and removed from the body. Engagement with the second driver will displace the lock body so that it interfaces with the flange so that the threaded fastener cannot be removed from the body by the second driver.

Description

TECHNICAL FIELD This disclosure relates generally to surgical instruments, systems, and methods, and more particularly to instruments, systems including driver-specific anti-backout features that allow different drivers to selectively operate components. , and methods. Such instruments, systems and methods may be used in a variety of procedures, for example orthopedic or neurological surgical procedures such as spinal fusion surgery.

Surgery is used to treat and cure a wide variety of diseases, illnesses, and injuries. Surgeons often need to access internal tissues through open or minimally invasive surgery. The term "minimally invasive" refers to all types of minimally invasive surgical procedures such as endoscopic, laparoscopic, arthroscopic, natural orifice endoluminal surgery, and natural orifice transluminal surgery. Minimally invasive surgery can have many advantages over traditional open surgical procedures, such as less trauma, faster recovery, less risk of infection, and less scarring.

In many surgical procedures, whether minimally invasive or not, it may be desirable to form a working channel within the patient to provide access to the surgical site within the patient. One such example is, for example, orthopedic or neurological surgery, including spinal fusion, in which a working channel is formed through the patient's tissue to allow the patient's vertebrae, and/or between adjacent vertebrae. It may be desirable to access an intervertebral disc that is placed in the spine.

Including various devices that are anchored to the operating table on which the patient is positioned, devices that penetrate tissue without being anchored to any other structure, or devices that anchor to multiple anchors implanted in the patient's bones. Various methods are known for providing such working channels. In such device configurations, the device may be improperly supported and may move undesirably relative to the patient when the patient moves relative to the operating table or other external structure; Or it may interfere with the surgeon or other user in performing some aspect of the procedure.

As an example, access to the intervertebral disc space can be difficult in spinal procedures involving manipulation on a patient's intervertebral disc placed between adjacent vertebrae. With the advent of modular pedicle screws, it may be possible to implant pedicle anchors prior to performing disc surgery. As a result, the retractor assembly is used to hold the surgical access site open for pedicle screw insertion and subsequent operation. However, retractor assemblies often require complex articulation of various retractor arms and blades to achieve an optimized access site. As such, retractor devices often employ multiaxial joints that can be selectively loosened and tightened during a surgical procedure; however, retractor device components that include multiaxial joints can be Must be disassembled and sterilized.

Thus, it ensures safe and secure options for locking mechanisms between instrument components to ensure that those locking mechanisms are not accidentally disassembled during a surgical procedure, as well as selectable locking mechanisms between specific components. Improved devices, systems and methods are needed that also allow for articulation and locomotion. For example, improved fastener assemblies are needed to allow multi-component devices to be reliably assembled and safely adjusted during surgical procedures without risking accidental disassembly. there is

Disclosed herein are surgical instruments, systems, and methods that provide backout prevention for screws used for polyaxial restraint and locking of components of a surgical retractor assembly. For example, embodiments described herein provide a fastener and threaded housing assembly that can be used to adjust the position of a polyball within a socket of a multiaxial joint using, for example, two different drivers. However, a first driver can be used to completely remove (e.g., retract) the fastener from the threaded housing, and a second driver can be used to adjust the position of the fastener within the housing. can only be used for Embodiments described herein may provide many advantages over conventional approaches. This includes, for example, the ability to prevent accidental separation of the fastener from the housing during a surgical procedure when using a dedicated driver tip to adjust the fastener, e.g. may include the ability to insert and remove fasteners from the housing with a second driver before or after a surgical procedure to sterilize separately.

an anti-backout mechanism defining a body configured to receive the fastener and defining a cavity configured to receive the head of the fastener when the fastener is disposed within the body; The cavity has a body having an inwardly extending flange defining a proximal opening of the cavity, a fastener having a threaded portion and a head portion, and at least one radially extending channel of the screw. a lock body disposed in each of the the head portion includes an upper socket configured to interface with a driver for adjusting the position of the fastener within the body; a lower socket; and at least one channel extending radially from the lower socket; and at least one channel sized and shaped to permit translation of the lock body therethrough. The anti-backout mechanism has a first configuration when the head portion of the fastener is engaged by the first driver and a second configuration when the head portion of the screw is engaged by the second driver. , has In the first configuration, engagement between the drive portion of the first driver and the upper socket of the head portion allows the fastener to move distally into the body without interference between the lock body and the flange of the cavity. Allows the locking body to move radially inward within the channel so that it can be inserted and removed proximally from the body. In a second configuration, when the fastener is disposed within the body such that the at least one radially extending channel is disposed distal to the flange of the cavity, the Engagement between the drive portion and the upper socket is such that when the fastener is advanced proximally by the second driver, the lock body is pulled out of the channel so that the fastener cannot be removed from the body by the second driver. Engagement of the distal end portion of the second driver with the lower socket of the head portion displaces the lock body radially outwardly to interfere with the flange.

In some examples, the lock body is a ball bearing. The cavity may define a length below the flange, the length of the cavity defining the maximum possible adjustment distance of the fastener within the body in the second configuration. The cavity may define a cylindrical inner wall and the flange is a radial flange. In some examples, the inner wall of the cavity defines a width that is greater than the diameter of the head portion of the fastener plus twice the extension distance of the lock body from the head portion in the second configuration.

The radially extending channel is configured to retain the lock body in a radially extending direction. The lower socket may define a cylindrical inner wall. The upper socket interfaces with the shape of the drive portions of the first and second drivers and allows torque to be transmitted from the drive portions to the fastener to adjust the position of the fastener within the body. A shape may be defined that is configured to. The body may include a threaded portion configured to receive the threaded portion of the fastener.

In some examples, in the first configuration, the position of maximum engagement between the drive portion of the first driver and the upper socket of the head portion is defined by contact between the drive shaft of the first driver and the upper socket. be done.

In some examples, in the second configuration, the maximum engagement position of the distal end portion of the second driver is defined by contact between the distal end portion and the bottom of the lower socket.

In some examples, in at least one of the first configuration or the second configuration, the maximum engagement position of the drive portion is between a drive feature of the drive portion and a corresponding drive feature within the upper socket. defined by contact between the ends.

Another example of the present disclosure includes a retractor body configured to couple to an implantable anchor, a first tissue manipulation tool coupled to the retractor body and capable of multi-axial movement relative to the retractor body, and a retractor. a second tissue manipulation instrument coupled to the body and capable of multi-axis movement relative to the retractor body. Each of the first tissue manipulation instrument and the second tissue manipulation instrument are coupled to the retractor body via a polyaxial joint, each joint having a screw for selectively locking the polyaxial joint against movement. Each operating implement and screw includes an anti-backout mechanism according to an embodiment of the present disclosure, wherein the operating implement includes a body of the anti-backout mechanism and the screw includes a fastener.

In some examples, the first and second tissue manipulation instruments face each other such that they can move either toward or away from each other.

The device may further comprise a lock coupled to the body and configured to interface with the anchor extension to selectively lock the position of the body relative to the anchor extension.

In some examples, each of the first tissue manipulation instrument and the second tissue manipulation instrument may be coupled to the body via a ball-and-socket joint. In some examples, each of the ball-and-socket joints includes an extension member configured to selectively lock the ball-and-socket joint against movement.

Another embodiment of the present disclosure is a body configured to receive a fastener, the body configured to receive the head of the fastener when the fastener is disposed within the body. a fastener having a body, a threaded portion and a head portion defining a cavity that defines an inwardly extending flange proximally of the cavity, the head portion including the body; an upper socket configured to interface with a driver for adjusting the position of the fastener within; a lower socket; and at least one channel extending radially from the lower socket, the lock body through the channel. and at least one channel sized and shaped to allow translation of the backout prevention system. The system also includes a locking body disposed in each of the at least one radially extending channel of the screw and a distal end sized and shaped to engage both the upper and lower sockets. A lock driver comprising a region, the distal end region having a drive portion and a lock portion located distal to the drive portion, the drive portion adjusting the position of the fastener within the body. and the locking portion is configured to be disposed within the lower socket when the drive portion is interfaced with the upper socket. and is sized and shaped to displace the locking body radially outward into a position that prevents the locking body within the fastener from being moved proximally past the flange; a lock driver; A standard driver with a distal end having a drive portion without a locking portion sized and shaped to move the locking body radially outward without interference between the locking body and the flange. Torque can be transmitted to the upper socket to proximally and distally adjust the position of the fastener within the body.

In some examples, the body is a first body and the system further comprises a second body configured to couple to the implantable anchor, the first body connecting to the second body. and defining at least a portion of a manipulation instrument configured to allow polyaxial movement relative to the second body, the tissue manipulation instrument coupled to the second body via the polyaxial joint; The position of the fastener within selectively locks the multiaxial joint against motion.

Yet another embodiment of the present disclosure is a method of assembling and aligning a fastener within a locking mechanism comprising inserting the fastener into a body of the locking mechanism and radially extending the fastener. The first driver is coupled with the fastener such that the locking body disposed within the existing channel is disposed distally of the inwardly extending flange within the cavity of the body; threading the fastener distally into engagement with the body using a driver; coupling a second driver to the fastener while the fastener is in threaded engagement with the body; The second driver drives the locking body radially outwardly so that it interferes with the flange of the channel to prevent proximal movement of the fastener beyond where the locking body interferes with the flange. A second driver is used by orienting, coupling, and screwing the fastener between the maximum proximal and distal positions defined by the interference between the lock body and the flange. and adjusting the position of the fastener within the body by using the body. In some examples, the lock body is a ball bearing.

In some examples, the body comprises a collet disposed within the socket, and inserting the fastener into the body couples the distal end of the fastener to an expansion member disposed within the collet. Including, whereby adjusting the position of the fastener within the body expands and contracts the collet within the socket to adjust the level of frictional engagement between the collet and the socket.

In some examples, the body is a first body defining at least a portion of the operating implement, the socket is a portion of a second body configured to couple to the implantable anchor, and The method further includes coupling the collet to the socket after inserting the fastener into the first body with the first driver, the collet and socket defining a multiaxial joint and the body using the second driver. Adjusting the position of the fastener within includes selectively locking the multi-axis joint against motion.

Any of the features or variations described above may be applied to any particular aspect or embodiment of this disclosure, in any number of different combinations. There is no explicit description of any particular combination, simply to avoid duplication in this summary.

The present disclosure may be more fully understood from the following detailed description read in conjunction with the accompanying drawings.
1A-1C are diagrams of one embodiment of a surgical instrument assembly in accordance with the teachings presented herein; Figure 2 is a detailed view of the retractor of the assembly of Figure 1; Figure 2 is an exploded view of the assembly of Figure 1; Figure 3 is an exploded view of the retractor of Figure 2; Figure 3 is a partially transparent detail view of the retractor of Figure 2; Figure 3 is a partially transparent bottom detail view of the retractor of Figure 2; FIG. 3 is a front perspective view of another embodiment of a surgical instrument assembly in accordance with the teachings presented herein; Figure 8 is a perspective view of an actuating instrument of the assembly of Figure 7; 8B is an alternative view of the actuating instrument of FIG. 8A; FIG. 8B is a partially transparent perspective view of the actuating instrument of FIG. 8A; FIG. 8 is a perspective view of the distal driver tip of the actuation instrument of the assembly of FIG. 7; FIG. 8 is a perspective view of an alternative distal driver tip for use with the actuation instrument of the assembly of FIG. 7; FIG. 3 is a partially transparent view of one embodiment of a driver-specific anti-backout assembly for use with the locking mechanism of the multi-axis joint of the retractor of FIG. 2; FIG. 11B is a cross-sectional view of the assembly of FIG. 11A showing the screw in the proximal position; FIG. 11B is a partially transparent view of the assembly of FIG. 11A showing the screw in the distal position; FIG. 11D is a cross-sectional view of the assembly of FIG. 11C; FIG. 11D is a partially transparent view of the driver-specific anti-backout assembly of FIGS. 11A-11D in use with the driver tip of FIG. 10B; FIG. 12B is a cross-sectional view of the assembly of FIG. 12A showing the screw in the distal position with the anti-backout driver tip partially inserted; FIG. 12B is a partially transparent view of the assembly of FIG. 12A showing the anti-backout driver tip fully inserted; FIG. 12D is a cross-sectional view of the assembly of FIG. 12C; FIG. 12B is a partially transparent view of the assembly of FIG. 12A showing the anti-backout driver tip fully inserted, the screw fully retracted, and the anti-backout mechanism engaging the internal flange of the body; FIG. Figure 12E is a cross-sectional view of the assembly of Figure 12E; 12B is a cross-sectional view of the assembly of FIG. 12A showing the screw in the proximal position with the anti-backout driver tip partially inserted; FIG. Figure 12G is a cross-sectional view of the assembly of Figure 12G; 12C is a top cross-sectional view of the driver-specific anti-backout assembly of FIGS. 11A-12H with the anti-backout driver tip disposed within the socket of the screw; FIG. 13B is a top cross-sectional view of the assembly of FIG. 13A with a standard driver tip disposed within the socket of the screw; FIG. 12H is a photograph of one embodiment of the driver-specific anti-backout assembly of FIGS. 11A-12H; FIG.

Specific illustrative embodiments are now described to provide a general understanding of the principles of construction, function, manufacture, and use of the apparatus and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. It will be appreciated by those skilled in the art that the apparatus and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments, and that the scope of the present disclosure extends beyond the scope of the claims. It will be understood that it is defined only by ranges. Features illustrated or described in connection with one exemplary embodiment may be combined with features of other embodiments. Such modifications and variations are intended to be included within the scope of this disclosure.

Furthermore, to the extent that linear or circular dimensions are used in describing the disclosed devices and methods, such dimensions are not intended to limit the types of shapes that can be used with such devices and methods. . Equivalents to such linear and circular dimensions can be determined for any geometric shape. Moreover, like-numbered components of the embodiments in this disclosure generally have similar features. In addition, the size and shape of the device and its components may vary depending on the anatomy for which the device will be used, the size and shape of the components with which the device will be used, and the components with which the device will be used. It can at least depend on the method and procedure to be followed.

1-6 illustrate an exemplary surgical instrument assembly 100 according to the teachings presented herein. Assembly 100 may be used in a variety of surgical procedures, including spinal surgery such as microsurgical osteotomies, spinal decompression, and spinal fusion. Generally, assembly 100 can include a support instrument 102 that couples to an implanted anchor 104, such as a pedicle screw or other bone screw. Assembly 100 can further include a retractor 106 coupled to support device 102 . Other components not shown herein may be included in or coupled to assembly 100 . Such components may include, for example, any of a variety of cameras or visualization systems, and any of a variety of other surgical instruments.

An exemplary method of using the assembly 100 of FIGS. 1-6 includes the following steps performed in any of a variety of sequences: a) making an incision in the patient's skin; percutaneously inserting an implantable anchor, such as a pedicle screw or other bone screw, through the incision; c) coupling the support device 102 to the implanted anchor (e.g., pedicle anchor); d) coupling a tissue retractor to the instrument; e) effecting medial-lateral retraction of the tissue surrounding the incision; f) coupling an optical visualization instrument to the tissue retractor and/or instrument; g) above. resecting a portion of the articular process and/or performing a microsurgery decompression procedure; h) removing the disc material, including removing the cartilaginous material from the vertebral endplates; i) The method may include one or more of inserting an interbody device and j) deploying a stabilization mechanism to stabilize the intervertebral segment.

The retractor assembly 106 described above, in combination with the support instrument or anchor extension 102 and the implanted anchor 104, for example, widens an incision made in the patient's skin and tissue to provide better access to the surgical site. can be used to enable By way of further example, in some embodiments, these components are anchored to a single implanted screw or anchor and can be placed in medial-lateral tissue to increase access for various surgical procedures. A setback assembly may be formed. Retracting the skin surrounding the incision and the underlying tissue medially and laterally provides a wider opening and working channel between the tissue manipulation tools to access the patient's spine or intervertebral space. obtain. In some embodiments, the working channel may extend to surround adjacent anchors implanted in adjacent vertebrae. Once the tissue in the incision wall has been retracted to form a working channel, any of a variety of surgical procedures are performed by introducing one or more instruments through the working channel defined by the tissue manipulation instrument of the retractor assembly. can be For example, procedures to the intervertebral disc space, such as disc replacement, discectomy, endplate preparation, fusion cage insertion, bone graft delivery, etc., can be performed by passing instruments or implants through the working channel.

Returning to FIGS. 1-6, FIG. 1 illustrates one embodiment of surgical instrument assembly 100 including support instrument 102 coupled to implantable anchor 104 and tissue retractor 106 . Further details regarding embodiments of assembly 100 can be found in U.S. patent application Ser. 16/139,434, entitled "PATIENT-MOUNTED SURGICAL RETRACTOR." Further details regarding embodiments of implantable anchors 104 can be found in US patent application Ser. Further details regarding specific embodiments of retractors that may be used in surgical assembly 100 can be found below and in US Pat. No. 7,491,168. The entire contents of each of these references are incorporated herein by reference.

In general, the support device may include an elongated body 108 formed at its distal end with a laterally extending fork that may interface with the narrow neck of anchor 104 . The fork may include opposed protrusions extending laterally from the distal portion of the elongate body and may be sized to receive a portion of the implantable anchor 104 in a U-shape. or otherwise define an open-ended recess. For example, the protrusion can be configured to fit around the proximal portion of the bone anchor, which can be part of a modular monoaxial or polyaxial pedicle screw. Such anchors may include a generally cylindrical distal shank portion having threads for tapping into bone, as well as a narrower neck proximal to the shank portion and a wider proximal head. The proximal head may be generally spherical or hemispherical in shape and may be configured to couple with the receiver head before or after implantation into the patient's bone. Elongated body can also include a lock configured to exert drag on the head of the anchor to control polyaxial movement of instrument 102 relative to anchor 104 . As shown in FIG. 3, the lock can include a lock body 302 that is coupled to the elongated body 108 and translates relative to the elongated body along a longitudinal axis 304 of the elongated body. It is possible. Locking body 302 may have a generally elongated shape to facilitate coupling with elongated body 108 and translation or sliding along or relative to elongated body. The lock may be actuated by a locking screw 305 that may cause distal translation of locking body 302 as it is further threaded into elongated body 108 . Lock body 302 may further include a laterally extending ring-shaped protrusion 306 at its distal end that contacts and engages the proximal head of anchor 104 . can be configured to exert a drag on the Ring-shaped protrusion 306 may define a lumen for maintaining access to drive features formed on the proximal end of the head of anchor 104 . This lumen, along with the lateral extension of protrusion 306 and the fork formed at the distal end of elongated body 108, is such that the longitudinal axis of the instrument is laterally offset from the longitudinal axis of anchor 104 or non-lateral. Instrument 100 can be oriented so that it is coaxial. Such a configuration may allow a driver or other instrument to access the drive features of anchor 104 even when instrument 100 is coupled. This allows flexibility for implanting the anchor 104 both before and after connecting the device 100 to the anchor 104 .

Returning to FIG. 2, a more detailed schematic of one embodiment of tissue retractor 106 is presented. Retractor 106 can include a body 202 that can be configured to couple to a support instrument or anchor extension 102 . First and second tissue manipulation instruments 204, 206 can be coupled to body 202 by rigid arms 208, 210, respectively, for example. Each of the first tissue manipulation tool 204 and the second tissue manipulation tool 206 may be capable of multi-axis motion with respect to the body via multi-axis joints 212, 214, such as ball-and-socket joints. Such joints may allow tissue manipulation instruments 204, 206 to move relative to each other in a variety of ways. For example, tools 204, 206 pivot toward or away from each other about axes that extend parallel to the longitudinal axis of support device 102 (eg, an axis parallel to axis 304 in FIG. 3). can be Tools 204 , 206 may also be pivoted toward or away from each other, eg, about axes that are transverse or oblique to axis 304 . For example, the tools 204, 206 can be moved ahead of each other, where the distal ends of the tools are moved towards or away from each other by a greater amount than the proximal ends of the tools. be. In some embodiments, moving the tip means that the proximal ends of the tools may or may not be moved towards each other while the distance between the proximal ends of the tools remains unchanged. and moving the distal ends of the tools away from each other. In addition, each multiaxial joint 212, 214 selectively locks the position of the associated tissue manipulation instrument 204, 206 or imposes a drag force that prevents movement in the absence of at least a threshold level of force. locks 216, 218 that can be used for

As described above, the tissue retractor 106 may be configured to couple to a support device or anchor extension 102 and such a retractor may be configured to adjust the height of the retractor relative to the implanted anchor 104 . It may be configured to slide along the length of the instrument. As shown in FIG. 2, the retractor body 202 can include a closed or partially open lumen or recess 220 that extends through the generally cylindrical elongated body 108 (FIG. 1). ), and is configured to receive a portion of the support device 102 . The retractor 106 has a retractor for the support device 102, such as a spring-loaded protrusion or pawl 222 that may engage a ratchet rack or other series of recesses or other surface features formed on the elongated body 108 of the support device. A feature for selectively locking the position of the retractor may also be included. Further, in some embodiments, locking feature 222 can be configured to prevent not only movement along the length of support device 102, but also rotation about it. The illustrated slide member or translational member is shown to allow the user to easily retract the projection 222 against the biasing force of a spring or other biasing element disposed within the body 202 of the retractor 106 . An actuator 224, such as a member, may be included.

In addition to adjusting the position of retractor 106 along the length of support instrument 102, the length of each of tissue manipulation tools 204, 206 may also be adjusted. For example, in some embodiments, tissue manipulation tools 204, 206 can each include extensions 226, 228 that can be configured to translate with respect to tissue manipulation tools 204, 206, respectively. By translating either extension 226, 228 proximally or distally with respect to the associated tool 204, 206, the overall length of the tool can be varied and, for example, the retractor 106 can extend the elongated body 108 of the support tool. The device may also be able to reach deeper into the tissue if it is worn above the patient's skin surface along the more proximal portion of the device.

FIG. 3 shows a partially exploded view showing how retractor 106 can be coupled to support instrument 102 by sliding the retractor down or distally over the proximal portion of the support instrument. For example, the recess or lumen 220 of the retractor 106 may be aligned with the generally cylindrical elongated body 108 of the support device, and the retractor may be advanced downwardly or distally along the axis 304 . While advancing the retractor relative to the support instrument, the user uses the sliding lever 224 to operate the spring-loaded pawl or protrusion 222 to allow free movement of the retractor relative to the support instrument. It can be retracted manually. Once the desired position has been reached, the user releases lever 224 to advance projection 222 to a complementary position formed on elongated body 108 to maintain the relative positioning of the retractor and support device. It may be adapted to engage recesses or other features. In other embodiments, complementary features formed on elongated body 108 and projection 222 may be formed as biased ratchets, where, for example, distal advancement of the retractor is , can be accomplished without actuating lever 224 , although proximal retraction of retractor 106 relative to instrument 102 requires actuating lever 224 to retract biased protrusion 222 .

4-6 show retractor 106 in various exploded and partially transparent views to better illustrate the interaction of the various components of retractor 106. FIG. For example, the multi-axis joints 212, 214 can be seen in more detail. Each multi-axis joint 212 , 214 may include a socket 402 , 404 formed in body 202 of retractor 106 . Each of the arms 208, 210 coupled to the tissue manipulation tools 204, 206 are internally formed such that various portions (e.g., petals 428) of the proximal end are deformable relative to other portions. It may have a generally ball-shaped proximal end 406, 408 (eg, collet) containing one or more relief slots. Locks 216, 218 are secured to each arm 208 by cooperation between threads 410, 412 formed on the locks and threads 414, 416 formed on the inner surfaces of through holes in arms 208, 210. , 210. Further, adjusting the position of lock 218 by movement along threads 412 moves expansion member 420 distally within ball-shaped proximal end 408 so as to urge petals 428 outwardly. Alternatively, the expansion member 420 can be retracted proximally so that the expansion member 420 seats further within the curved inner surface of the petals 408 and does not urge the petals outwardly. Disposed at the distal ends of the locks 216 , 218 may be configured and arranged within the ball-shaped distal end 408 . Lock assembly 499 can include lock 218 and a portion of arm 210 to which lock 218 is operably coupled.

When assembled, the extension members 418, 420 allow the extension members 418, 420 to be disposed within one of the sockets 402, 404 of the body 202, as shown in FIGS. In an unlocked (eg, retracted) position, it may be disposed within the generally ball-shaped proximal ends 406, 408. FIG. In order to lock the ball-shaped proximal end 406, 5408 into and against one of the sockets 402, 404, the locks 216, 218 are arranged such that the extension member 420 connects the arms 208, 210 and the locks 216, 218 can be rotated with respect to arms 208 , 210 so as to be further advanced into ball-shaped proximal end 408 . Advancement of locks 216, 218 into ball-shaped proximal end 408 causes extension members 418, 420 formed at the distal end of each lock to petal radially outward inside sockets 402, 404. 428 can be extended. As the petals 428 of the ball-shaped proximal ends 406,408 expand radially, they are forced into contact with the sidewalls of the sockets 402,404. This can cause an increase in frictional forces between the sockets 402,404 and the ball-shaped proximal ends 406,408 of the arms 208,210. Further, when the locks 216, 218 are sufficiently advanced, the force of the extension members 418, 420 against the petals 428 effectively locks the ball-shaped proximal ends 406, 408 in place, thereby allowing the arms to Any movement of 208, 210 or the tissue manipulation tools 204, 206 coupled thereto may be prevented.

FIG. 7 shows an alternative embodiment of surgical instrument assembly 1000 including support instrument 1002 coupled to implantable anchor 104 and tissue retraction assembly 1006 . Also shown is an embodiment of a driver 1008 that can be used to actuate locks 1010, 1012 that can selectively permit or prevent multi-axis movement of opposing tissue manipulation instruments 1014, 1016 relative to body 1018 of retraction assembly 1006. ing.

8A-9 show driver 1008 in more detail. In some embodiments, the driver 1008 can include a housing 1802 disposed around a drive shaft 1804 that connects to a handle 1806 at its proximal end. A distal end 1812 of the drive shaft 1804 can be configured to interface with proximal ends of the locks 1010, 1012 of the tissue retractor assembly 1006 to apply actuation torque. Driver 1008 may also include a stabilizing shaft 1810 coaxially disposed about drive shaft 1804 and coupled to housing 1802 and interface 1808 . The interface 1808 may include opposing slots or notches 1814, 1816 that allow the interface to engage the locks 1010, 1012 such that the distal end 1812 of the drive shaft 1804 engages the lock. each portion of one of the arms 1302, 1304 when disposed on one of the arms 1302, 1304. The user may then hold housing 1802 steady to counter any tendency of retractor assembly 1006 to rotate or otherwise move in response to pivoting of handle 1806 . More specifically, the rigid, non-rotating connection between housing 1802, stabilizing shaft 1810, and interface 1808, combined with the inability of interface 1808 to rotate relative to arms 1302, 1304 due to slots 1814, 1816. , may provide useful stability as the user pivots the handle 1806 while holding the base 1802 .

One problem that arises with the types of instruments described above is that the user may unintentionally overextend the screws 419 of the locks 216, 218 during the procedure. This can cause the screw 419 to be separated from the threads 414, 416 of the tissue manipulation instrument arms 208, 210. FIG. To prevent this, embodiments of the present disclosure provide locks, also called polyball tightening screws, a mechanism to prevent the screws 419 of 216, 218 from being unintentionally removed during the procedure. However, because screw 419 also needs to be disassembled for cleaning and initial assembly, screw 419 needs to be selectively removable beyond its backstop. Accordingly, an anti-backout mechanism is provided and described herein that allows selective removal of screw 419 past the backstop. Although this mechanism may be added to the locking assembly 499, backing out the screw 419 is required to allow the petal 428 of the ball-shaped proximal end 408 to be crushed and inserted into the socket 404. , however, fully backing out completely disengages screw 419 from threads 416 and/or extension member 420 . This allows the user to be notified when the screw 419 has backed out sufficiently and/or removes the screw 419 from the extension member 420 while still allowing adjustment of the screw 419 to allow for adjustment of the lockout assembly 499 . A need arises for a backstop to prevent unintentional separation of the .

One purpose of the anti-backout mechanism is to permanently capture the screw or lock 218 because it is undesirable due to the problems posed when sterilizing the components. to allow backout prevention to occur without For example, assembly 499 may need to be completely disassembled after use and each component thoroughly sterilized, which involves separating screw 419 from threads 416 and expanding member It becomes necessary to separate 420 from screw 419 . Complete disassembly is not possible and thorough cleaning and sterilization can be difficult when more traditional captive screws are utilized to prevent unintentional backout. Accordingly, the present disclosure provides a mechanism for selective backout prevention based on the driver utilized by the user, thereby enabling selective prevention of backout during a procedure, but not cleaning and sterilization. Complete decomposition for As will be described in more detail below, lockout assembly 499 is a backing screw that allows screw 419 to be assembled or disassembled or adjusted with a first driver and adjusted with a second driver. A second driver may include a fastener (e.g., screw 419) and a body (e.g., a portion of arm 210 that receives screw 419) that cooperate to provide an out-prevention mechanism; cannot be used to disassemble or back out the

FIG. 10A is a perspective view of one embodiment of a driver tip 1813 of distal end 1812 that may be utilized, for example, on actuator 1008 of the assembly of FIG. The device configuration of Figure 10A may also be referred to as a standard driver. As will be described in more detail below, standard driver 1812 may be used to lock assembly 499 (or lock assembly 599 as shown in FIGS. 11A-14), including initial assembly or subsequent disassembly of lock assembly 499. It can be used to perfectly adjust the positioning of locks 218 or other fasteners within. 10B is a perspective view of an alternative distal driver tip for use with the actuator of the assembly of FIG. 7; FIG. FIG. 10B shows an anti-backout driver 1901 that includes a distal end 1912 that is divided into two distinct regions: a proximal driver tip 1913, a driver tip 1913 and a distal tip. and a distal interference element 1914 extending between the distal end of section 1912 . In operation, the fastener or lock 218 is disassembled or completely backed out of the body 210 using the anti-backout driver 1901 in conjunction with the lock assemblies 499, 599, as discussed in more detail below. to prevent

Although the driver tips 1813, 1913 are shown in FIGS. 10A and 10B as having a hexalobed drive feature, this is one of many common driver features and is by way of example only. is shown. Many different driver functions can be used with the embodiments disclosed herein.

11A-11D are partially transparent and cross-sectional views of a driver-specific anti-backout assembly 599 for use with the screw 419 and lock 218 of the retractor multiaxial joint of FIG. 11A is a partially transparent view and FIG. 11B is a cross-sectional view, both of which have driver specific backout prevention with a standard driver 1812 disposed within socket 2218 of screw 519 disposed within body 2210. Assembly 599 is shown. Body 2210 can be, for example, the portion of arm 210 that receives screw 519 . Screw 519 may have a threaded portion that screws into a corresponding threaded portion of body 2210 . However, in some examples, body 2210 and the portion having corresponding threads 416 may be separate pieces, and in still other examples, screw 519 and body 2210 may comprise a pin and channel system, Or they may be connected by means other than threads, such as other means known in the art. Body 2210 in turn defines cavity 2215 for receiving head portion 2218 or socket of screw 519 . Cavity 2215 includes an inwardly extending flange 2211 or protrusion that functions as a backstop when the anti-backout driver is disposed within head portion 2218 (as shown in FIGS. 12A-12H). .

11A and 11B, the head portion of screw 419 defines an upper socket 2220 and a lower socket 2250 and drive tip 1813 can only engage upper socket 2220 . Head portion 2218 also includes one or more channels 2219 extending radially from lower socket 2250 . Each channel 2219 includes a lock body, such as ball bearings 2240 as shown. In operation, anti-backout assembly 599 allows ball bearings 2240 disposed within channels 2219 to be deflected radially inwardly by flanges 2211 at least partially into lower sockets 2250 as shown. Thus, it does not interfere with the flange 2211, allowing a standard driver 1812 to fully insert the screw 519 into and fully remove the screw 519 from the body 2210. 11A and 11B show anti-backout assembly 599 in the "up" position with standard driver 1812, where the male hexalobe feature of driver tip 1813 is female in upper socket 2220. Bottoming out on the mold lobes, the ball bearings 2240 are free to move inwards allowing removal of the screws 519 from the body 2210 . FIGS. 11C and 11D show anti-backout assembly 599 in the “down” position with standard driver 1812 . Additionally, distal advancement of screw 419 is limited by the interaction of the distally facing surface of head portion 2218 with the proximally facing surface of the cavity, as shown in FIG. 11D.

12A-12H are partially transparent and cross-sectional views of the driver-specific anti-backout assembly 599 of FIGS. 11A-11D in use with the anti-backout driver 1901 of FIG. 10B. 12A and 12B show the insertion of the distal end 1912 of the anti-backout driver 1901 into the head portion 2218 of the screw, with the screw 519 in the "down" position and the interference element 1914 positioned within the upper socket 2220. is set. In this position, interference element 1914 cannot engage upper socket 2220 to drive screw 519 because interference element 1914 lacks an engagement feature. In addition, ball bearing 2240 is free to move without being constrained by anything disposed within lower socket 2250 .

Full insertion of distal interference element 1914 into lower socket 2250 is shown in FIGS. Bottoming out (eg, female lobe), the interference element 1914 is disposed within the lower socket 2250 . The presence of interfering element 1914 causes ball bearing 2240 to be displaced radially outward from head portion 2218 until it extends into cavity 2215 of body 2210 . As shown in FIGS. 12E and 12F, ball bearing 2240 extends from the head portion beyond the outer diameter of the head portion to a distance where it interferes with flange 2211 when screw 519 is driven proximally.

12E and 12F, anti-backout driver 1901 is used to back out screw 519 from body 2210 until ball bearing 2240 reaches a position of interference with flange 2211 (indicated by circle 2299). . Since the presence of interference element 1914 in lower socket 2250 will prevent ball bearing 2240 from moving radially inward beyond the inner diameter of flange 2211, anti-backout driver 1901 is shown as The screw 519 cannot be backed out beyond the position. Thus, when the screw 519 is disposed within the body 2210 with the channel 2219 past the flange 2211 , the anti-backout driver 1901 will cause the locking ball bearing 2240 to engage the cavity 2215 when the locking ball bearing 2240 abuts the flange 2211 . It can only be used to adjust the position of screw 519 as allowed below head portion 2218 by length 2299 .

12G and 12H show the removal of the anti-backout driver 1901 from the head portion 2218, thereby freeing the ball bearings to move radially inward into the lower socket 2250, thereby freeing the screw. 519 can be retracted proximally over flange 2211 using, for example, standard driver 1812 .

13A and 13B are top cross-sectional views of lower socket 2250 of the driver-specific anti-backout assembly of FIGS. 13B shows the ball bearings 2240 in their displaced position, FIG. Ball bearing 2240 is shown in the “free” position when there is sufficient room in lower socket 2250 to move. In some embodiments, as shown in FIG. 13B, the channel 2219 has an inner abutment 2251 to prevent the ball bearing from falling into the lower socket 2250 and out of the channel 2219. can include In some embodiments, channel 2219 can include outer abutments 2251 to prevent ball bearings from falling out of head portion 2218 when head portion 2218 is removed from body 2210 .

Although the lock body is shown as a ball bearing 2240, other lock bodies such as pins are also contemplated to ensure that the lock body does not get stuck in the interference position and to prevent separation of screw 519. , which biases the lock body inwardly.

FIG. 14 is a photograph of one embodiment of the driver-specific anti-backout assembly 599 of FIGS. Cavity 2215 (not shown) and screw configured to adjust the position of a tapered member (not shown) disposed at the end of the screw with respect to the conical inner surface of the proximal end 408 of the 519, the ball-shaped distal end 408 of the body 2210 is shown. A head portion 2218 of screw 519 includes a ball bearing 2240 disposed within channel 2219 . FIG. 14 also shows an exemplary anti-backout driver 1901 having a driver 1913 and an interference element 1914 configured to engage a socket in head portion 2218, as described herein. .

Note that any order of method steps expressed or suggested in the above description or accompanying drawings should not be construed as limiting the disclosed method to performing the steps in that order. should. Rather, the various steps of each of the methods disclosed herein can occur in any of various orders. Moreover, the methods described are merely exemplary embodiments, and various other methods, including additional steps or fewer steps, are within the scope of the disclosure.

The instruments disclosed herein can be constructed from any of a variety of known materials. Exemplary materials for use in surgical applications include, for example, metals such as stainless steel, titanium, nickel, cobalt chromium, or alloys and combinations thereof, polymers such as PEEK, ceramics, carbon fiber, and the like. Suitable materials are listed. Various components of the instruments disclosed herein can have varying degrees of stiffness or flexibility appropriate for their use. The size of the device can also vary greatly depending on the intended use and the anatomy of the surgical site. Additionally, certain components may be formed from different materials than other components. One or more components or portions of the instrument may be formed from radiopaque materials or other structural components to facilitate visualization under fluoroscopy and other imaging techniques. It may be formed from a radiolucent material so as not to interfere with visualization. Exemplary radiolucent materials include carbon fiber and high strength polymers.

The devices and methods disclosed herein can be used in minimally invasive and/or open surgery. Although the devices and methods disclosed herein are generally described in the context of spinal surgery on human patients, the methods and devices disclosed herein can be used in a variety of ways with any human or animal subject. It will be appreciated that it can be used in any surgical procedure or in a non-surgical procedure.

The devices disclosed herein can be designed to be discarded after a single use, or can be designed to be used multiple times. In either case, however, the device can be reconditioned for reuse after at least one use. Reconditioning can include any combination of the steps of disassembly of the device, followed by cleaning or replacement of particular parts, and subsequent reassembly. Specifically, the device can be disassembled and any number of the particular parts or portions of the device can be selectively replaced or removed in any combination. After cleaning and/or replacement of particular parts, the device can be reassembled for later use either at a reconditioning facility or by the surgical team immediately prior to the surgical procedure. Those skilled in the art will appreciate that reconditioning of the device can utilize a variety of techniques for disassembly, cleaning/replacement, and reassembly. Use of such techniques, and the resulting reconditioned device, are all within the scope of the present application.

The devices described herein may be processed prior to being used in a surgical procedure. First, a new or used instrument may be obtained and cleaned if necessary. The instruments can then be sterilized. In one sterilization technique, the instrument may be placed in a closed and sealed container, such as a plastic bag or a TYVEK bag. The container and its contents may then be placed in a radiation field capable of penetrating the container, such as gamma rays, X-rays, or high energy electrons. Radiation can kill bacteria on the device and in the container. After this, the sterilized instrument can be stored in the sterile container. The sealed container can keep the instrument sterile until it is opened in the medical facility. Other forms of sterilization known in the art are possible. This can include beta rays or other radiation, ethylene oxide, steam, or liquid baths (eg, cold soak). Depending on the materials used, the presence of electrical components, etc., certain forms of sterilization techniques may be more suitable for use on different parts of the device.

Those skilled in the art will appreciate further features and advantages based on the above-described embodiments. Accordingly, the present disclosure is not to be limited by what has been specifically shown and described. All publications and references cited herein are expressly incorporated herein by reference in their entirety.

[Mode of implementation]
(1) A backout prevention mechanism,
A body configured to receive a fastener, said body defining a cavity configured to receive a head of said fastener when said fastener is disposed within said body. a body, wherein said cavity has an inwardly extending flange defining a proximal opening of said cavity;
A fastener having a threaded portion and a head portion, the head portion comprising:
an upper socket configured to interface with a driver for adjusting the position of the fastener within the body;
a lower socket;
at least one channel extending radially from said lower socket, said at least one channel being sized and shaped to permit translation of a lock body through said channel. and,
a locking body disposed in each of said at least one radially extending channel of said screw;
The anti-backout mechanism has a first configuration when the head portion of the fastener is engaged by a first driver and a first configuration when the head portion of the screw is engaged by a second driver. a second configuration;
In the first configuration, engagement of the drive portion of the first driver and the upper socket of the head portion is achieved without interference between the lock body and the flange of the cavity such that the fastener is allowing the locking body to move radially inwardly within the channel so that it can be inserted distally into and removed proximally from the body;
In the second configuration, when the fastener is disposed within the body such that the at least one radially extending channel is disposed distal to the flange of the cavity , the engagement of the drive portion of the second driver with the upper socket is such that the fastener cannot be removed from the main body by the second driver. of the distal end portion of the second driver and the head portion to displace the locking body radially outwardly so that the locking body interferes with the flange of the channel when advanced into the An anti-backout mechanism that includes engagement with the lower socket.
(2) The backout prevention mechanism according to claim 1, wherein the lock body is a ball bearing.
(3) wherein said cavity defines a length below said flange, said length of said cavity defines a maximum possible adjustment distance of said fastener within said body in said second configuration; A backout prevention mechanism according to aspect 1 or 2.
4. An anti-backout mechanism according to any preceding claim, wherein the cavity defines a cylindrical inner wall and the flange is a radial flange.
(5) said inner wall of said cavity defines a width greater than the diameter of said head portion of said fastener plus twice the extension distance of said lock body from said head portion in said second configuration; 5. The backout prevention mechanism according to embodiment 4, wherein:

Clause 6. The anti-backout mechanism of any preceding clause, wherein the radially extending channel is configured to retain the lock body in the radially extending direction. .
7. An anti-backout mechanism according to any preceding claim, wherein the lower socket defines a cylindrical inner wall.
(8) said upper socket interlocks with the shape of said drive portions of said first driver and said second driver and includes said drive portion for adjusting said position of said fastener within said body; 8. An anti-backout mechanism according to any of the preceding embodiments, defining a shape configured to facilitate transmission of torque from a portion to the fastener.
Clause 9. The anti-backout mechanism of any of clauses 1-8, wherein the body comprises a threaded portion configured to receive the threaded portion of the fastener.
(10) In the first configuration, the maximum engagement position between the drive portion of the first driver and the upper socket of the head portion is between the drive shaft of the first driver and the upper socket. 10. An anti-backout mechanism according to any preceding embodiment, wherein the anti-backout mechanism is defined by the contact of the .

(11) In the second configuration, the maximum engagement position of the distal end portion of the second driver is defined by contact between the distal end portion and the bottom of the lower socket. A backout prevention mechanism according to any one of aspects 1-10.
(12) In at least one of said first configuration or said second configuration, wherein the maximum engagement position of said drive portion is such that a drive feature of said drive portion and a corresponding drive feature within said upper socket; 12. An anti-backout mechanism according to any preceding embodiment, defined by contact between the ends of the parts.
(13) A surgical instrument comprising:
a retractor body configured to couple to the implantable anchor;
a first tissue manipulation tool coupled to the retractor body and capable of multi-axis motion with respect to the retractor body;
a second tissue manipulation instrument coupled to the retractor body and capable of multi-axis motion with respect to the retractor body;
each of the first tissue manipulation tool and the second tissue manipulation tool coupled to the retractor body via a multiaxial joint;
each joint includes a screw for selectively locking said multi-axis joint against motion;
Each manipulating instrument and screw comprises an anti-backout mechanism according to any of embodiments 1-12, the manipulating implant comprising the body of the anti-backout mechanism, and the screw comprising the fastener. Surgical instruments, including
Aspect 14. Aspect 13, wherein the first tissue manipulation instrument and the second tissue manipulation instrument face each other such that they can move either toward or away from each other. instrument.
Clause 15. Aspect 13 or 14, further comprising a lock coupled to the body and configured to interface with the anchor extension to selectively lock the position of the body relative to the anchor extension. instrument.

(16) The instrument according to any one of embodiments 13-15, wherein each of the first tissue manipulation instrument and the second tissue manipulation instrument is coupled to the body via a ball-and-socket joint.
17. The apparatus of any of clauses 13-16, wherein each of the ball and socket joints includes an expansion member configured to selectively lock the ball and socket joint against movement.
(18) A backout prevention system comprising:
A body configured to receive a fastener, said body defining a cavity configured to receive a head of said fastener when said fastener is disposed within said body. a body, wherein said cavity defines an inwardly extending flange at a proximal location of said cavity;
A fastener having a threaded portion and a head portion, the head portion comprising:
an upper socket configured to interface with a driver for adjusting the position of the fastener within the body;
a lower socket;
at least one channel extending radially from said lower socket, said at least one channel being sized and shaped to permit translation of a lock body through said channel. and,
a locking body disposed in each of said at least one radially extending channel of said screw;
A lock driver comprising a distal end region sized and shaped to engage both the upper socket and the lower socket, the distal end region connecting a drive portion to the drive portion; and a distally located locking portion, wherein the drive portion interfaces with the upper socket to transmit torque to the fastener to adjust the position of the fastener within the body. wherein the locking portion is configured to be disposed within the lower socket when the drive portion is interfaced with the upper socket; and the locking body within the fastener. a lock driver sized and shaped to displace the lock body radially outward into a position that prevents the lock body from being moved proximally beyond the flange;
A standard driver with a distal end having a drive portion without a locking portion sized and shaped to move the locking body radially outward reduces interference between the locking body and the flange. an anti-backout system capable of transmitting torque to the upper socket to proximally and distally adjust the positions of fasteners within the body without the backout.
(19) the body is a first body, and the system further comprises a second body configured to couple to an implantable anchor;
said first body defining at least a portion of a manipulator connected to said second body and configured to allow polyaxial movement relative to said second body;
the tissue manipulation instrument is coupled to the second body via a polyaxial joint;
19. The backout prevention system of embodiment 18, wherein the position of the fastener within the first body selectively locks the multi-axis joint against movement.
(20) A method of assembling and adjusting the position of a fastener within a locking mechanism comprising:
inserting the fastener into the body of the locking mechanism;
The first driver such that a locking body disposed within a radially extending channel of the fastener is disposed distally of an inwardly extending flange within a cavity of the body. with the fastener and using the first driver to distally screw the fastener into engagement with the body;
coupling a second driver to the fastener while the fastener is in threaded engagement with the body, the second driver positioning a position where the lock body interferes with the flange; displacing the locking body radially outwardly so that the locking body interferes with the flange of the channel to prevent proximal movement of the fastener beyond;
By screwing the fastener between a maximum proximal position and a maximum distal position defined by the interference between the lock body and the flange, the second driver is used to and adjusting the position of the fastener.

21. The method of claim 20, wherein the lock body is a ball bearing.
(22) the body comprises a collet disposed within a socket, and inserting the fastener into the body couples a distal end of the fastener to an expansion member disposed within the collet; whereby adjusting the position of the fastener within the body expands and contracts the collet within the socket to adjust the level of frictional engagement between the collet and the socket. 22. A method according to embodiment 20 or 21, which is to be adjusted.
(23) the body is a first body defining at least a portion of a manipulation instrument, the socket is a portion of a second body configured to couple to an implantable anchor, and the The method further includes coupling the collet to the socket after inserting the fastener into the first body with the first driver, wherein the collet and socket define a multiaxial joint; 23. The method of embodiment 22, wherein adjusting the position of the fastener within the body using two drivers comprises selectively locking the multi-axis joint against movement.

Claims (15)

A backout prevention mechanism,
A body configured to receive a fastener, said body defining a cavity configured to receive a head of said fastener when said fastener is disposed within said body. a body, wherein said cavity has an inwardly extending flange defining a proximal opening of said cavity;
A fastener having a threaded portion and a head portion, the head portion comprising:
an upper socket configured to interface with a driver for adjusting the position of the fastener within the body;
a lower socket;
at least one channel extending radially from said lower socket, said at least one channel being sized and shaped to permit translation of a lock body through said channel. and,
a locking body disposed in each of said at least one radially extending channel of said screw;
The anti-backout mechanism has a first configuration when the head portion of the fastener is engaged by a first driver and a first configuration when the head portion of the screw is engaged by a second driver. a second configuration;
In the first configuration, engagement of the drive portion of the first driver and the upper socket of the head portion is achieved without interference between the lock body and the flange of the cavity such that the fastener is allowing the locking body to move radially inwardly within the channel so that it can be inserted distally into and removed proximally from the body;
In the second configuration, when the fastener is disposed within the body such that the at least one radially extending channel is disposed distal to the flange of the cavity , the engagement of the drive portion of the second driver with the upper socket is such that the fastener cannot be removed from the main body by the second driver. of the distal end portion of the second driver and the head portion to displace the locking body radially outwardly so that the locking body interferes with the flange of the channel when advanced into the An anti-backout mechanism that includes engagement with the lower socket. 2. The anti-backout mechanism of claim 1, wherein said lock body is a ball bearing. 2. The cavity defines a length below the flange, the length of the cavity defining a maximum possible adjustment distance of the fastener within the body in the second configuration or 2. The backout prevention mechanism according to 2. An anti-backout mechanism according to any preceding claim, wherein the cavity defines a cylindrical inner wall and the flange is a radial flange. wherein said inner wall of said cavity defines a width greater than the diameter of said head portion of said fastener plus twice the extension distance of said lock body from said head portion in said second configuration. Item 5. The backout prevention mechanism according to item 4. An anti-backout mechanism according to any preceding claim, wherein the radially extending channel is configured to retain the lock body in the radially extending direction. An anti-backout mechanism according to any preceding claim, wherein the lower socket defines a cylindrical inner wall. The upper socket interfaces with the shape of the drive portions of the first driver and the second driver, and includes a socket from the drive portion to the fastener for adjusting the position of the fastener within the body. An anti-backout mechanism according to any one of claims 1 to 7, defining a shape configured to allow transmission of torque to and from the backout prevention mechanism. An anti-backout mechanism according to any preceding claim, wherein the body comprises a threaded portion configured to receive the threaded portion of the fastener. In the first configuration, the position of maximum engagement between the drive portion of the first driver and the upper socket of the head portion is determined by contact between the drive shaft of the first driver and the upper socket. An anti-backout mechanism as defined in any one of claims 1-9. Claims 1-, wherein, in the second configuration, a position of maximum engagement of the distal end portion of the second driver is defined by contact between the distal end portion and the bottom of the lower socket. 11. An anti-backout mechanism according to any one of clause 10. In at least one of the first configuration or the second configuration, the maximum engagement position of the drive portion is an end of a drive feature of the drive portion and a corresponding drive feature in the upper socket. An anti-backout mechanism according to any one of claims 1 to 11, defined by contact between the parts. A surgical instrument,
a retractor body configured to couple to the implantable anchor;
a first tissue manipulation tool coupled to the retractor body and capable of multi-axis motion with respect to the retractor body;
a second tissue manipulation instrument coupled to the retractor body and capable of multi-axis motion with respect to the retractor body;
each of the first tissue manipulation tool and the second tissue manipulation tool coupled to the retractor body via a multiaxial joint;
each joint includes a screw for selectively locking said multi-axis joint against motion;
Each operating tool and screw comprises an anti-backout mechanism according to any one of claims 1 to 12, said operating tool comprising said body of said anti-backout mechanism and said screw comprising said fastener. , surgical instruments. 14. The instrument of claim 13, wherein the first tissue manipulation tool and the second tissue manipulation tool face each other such that they can move either toward or away from each other. 15. The instrument of claim 13 or 14, further comprising a lock coupled to the body and configured to interface with the anchor extension to selectively lock the position of the body relative to the anchor extension.

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